1. Field of the Invention
The present invention concerns an obturator ring for valves of the butterfly valve type.
2. Description of the Prior Art
Butterfly valves are used, notably in fluid circuits, to stop or not stop the flow of fluid in at least a part of the circuit. For this type of valve to work properly, a high degree of imperviousness must be obtained, in the closed position, between the obturator element or flap and the valve body.
To this effect, a obturator ring is most commonly used. This obturator ring consists of a continuous circular seal. This circular seal is mounted in a groove, made on the edge of the flap. In the closed position, this circular seal comes into contact with a cylindrical bearing surface of the valve body.
A obturator ring of this type has a certain number of drawbacks. In particular, there are residual leaks as the fluid flows partly between the obturator ring and the groove of the flap. Furthermore, the use of a continuous, ring-shaped seal causes problems in assembly. In general, the body of the flap has to be machined to make a part of the groove and an additional end plate is added to the flap to hold the obturator ring in position.
Furthermore, when the butterfly valve has to be used in fluid circulation circuits having to work under a wide range of pressures which may vary between 500 millibars and 24 bars and under temperatures which may vary between ambient temperature and 600.degree. C., it is difficult to make an obturator ring which works properly at all the above-mentioned pressures and temperatures. The compromise torque is modified according to temperatures and pressures.